XAOSIM atmospheric phase screens

Pick your favorite stargazing spot and document yourself about the properties of the atmospheric seeing for that time of the year.

import xaosim as xs
csz = 400
atmo = xs.Phscreen(
        name="MaunaKea", csz=400, lsz=8.0,
        r0=0.5, L0=10, fc=19.5, correc=1.0,
        shdir="/dev/shm/", shmf="maunakea.wf.shm")

The parameters that are passed along are:

• name is a human readable label,
• csz is again, the size of the array used for the computation,
• lsz is the linear physical size of the array (here equal to the telescope pupil diameter of 6 meters),
• r0 is the size of the Fried parameter (in meters),
• L0 is the size of the outer scale parameter (in meters),
• fc is the AO cutoff frequency expressed in number of cycles across the aperture (don't worry about it now),
• correc is the uniform AO correction gain over the range of possible spatial frequencies (here again, it will make sense later),
• shdir is the directory where the camera SHM data structure will be written,
• shmf is the name of the SHM data structure itself. Notice that we use a different .wf.shm extension, which is only used in the context of these XAOSIM simulations.

I won't get into a lecture about atmospheric turbulence and will assume that you know what the Fried and the outer scale parameters are. If you don't, then I encourage you to do a little research online. As for the two mysterious fc and correc, their description and the rationale for their existence will be provided below.

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